The drill steering apparatus similar to the present invention is disclosed in my prior U.S. Pat. No. 4,394,881. In such apparatus, stabilizer rings are mounted by retaining rings on the drill string one being immediately above the drill bit and another being spaced thereabove on the drill string. In each stabilizer ring are pistons, the upper of which has pistons which sense the low side of the well bore and the lower of which has pistons which exert a preselected force on the drill string responsive to the sensing of the low side of the well bore by the upper pistons. In this manner, the apparatus creates side thrusts on the drill bit which cause it to proceed in the well bore in the desired direction.
In the use of this apparatus, difficulty has been encountered in that the tool rotated within the stabilizer rings so that the stabilizers could not be rotated to ensure that the stabilizer rings could pass easily through tight spots and ledges which are prevalent in a well bore. Additionally, the retaining rings positioned above and below each of the stabilizer rings rotated with the drill string and their engagement of the ends of the stabilizer body creates sufficient heat to cause a failure of seals at the surface of the body ends and the retaining rings.
In the past stabilizers have long been used in the drilling of well bores to support the drill collars in directional drilling to control the angle of drilling. Such drill collars were tightly secured to the drill collar. Examples of such stabilizers are shown in U.S. Pat. Nos. 4,011,918 and 4,275,935.
In order to resolve the problem encountered by the stabilizer rings of the drill steering tool in moving through tight spots, the rotation of the drill string or tool body through the stabilizer ring had to be avoided so that the stabilizer ring could be rotated.
Another disadvantage of the prior steering tool was the accumulation of solids material between the stabilizer rings and the steering body which interfered with the operation of the steering apparatus.